This invention relates to a pressure actuated switch and more particularly to a pressure actuated switch which is rugged, durable, and highly reliable, while having a comparatively simplified construction and being economically manufacturable.
Pressure actuated switches of various types have been employed in numerous applications where the pressure condition of a pressure source or line must be converted to an electrical signal. Exemplary of existing pressure switches are those disclosed in the following patents: U.S. Pat. No. 2,928,913 issued to H. L. Dobrikin on Mar. 15, 1960; U.S. Pat. No. 2,935,581 issued to H. L. Dobrikin on May 3, 1960; U.S. Pat. No. 3,093,716 issued to C. Horowitz on June 11, 1963; U.S. Pat. No. 3,177,313 issued to B. Klimek on Apr. 6, 1965; U.S. Pat. No. 3,240,895 issued to C. Horowitz and B. Klimek on Mar. 15, 1966; U.S. Pat. No. 3,519,773 issued to B. Klimek on July 7, 1970; and U.S. Pat. No. 3,529,107 issued to H. L. Dobrikin on Sep. 15, 1970.
Pressure actuated switches may include an actuating member which is carried by or part of a diaphragm, piston or other means operated by fluid pressure thereagainst, spring means being provided for urging the actuating member in one direction. Various types of housing and contact arrangements may be employed. In one arrangement, a housing is formed from a pair of members which have rim portions secured together by suitable means, with electrical contacts being secured to one of such members which may also carry the spring means of the switch. In one type of contact arrangement, a contact is carried by an actuating member for movement into and out of engagement with a fixed contact or fixed contacts.
Such arrangements as well as others are generally satisfactory but may be more difficult and expensive to manufacture than would be desirable. Accordingly, it is an object of this invention to provide an improved pressure actuated switch which is highly reliable in operation while being readily and economically manufacturable.
Another object of the invention is to provide a switch construction in which desired alternative switching actions can be readily obtained.
In an illustrative embodiment of a switch constructed in accordance with this invention, first and second resilient contact plates have portions engaged with planar surface portions of a housing, such surface portions being disposed approximately in a common plane transverse to a central axis, in radially spaced relation to the central axis and in arcuately spaced relation to each other. The contact plates have overlapping end portions which carry first and second interengagable contacts and an actuating member is movable along the central axis and has a portion projecting outwardly to engage a portion of one of the plates and to control deflection thereof and interengagement of the contacts.
This arrangement simplifies the construction of a switch and has other advantages. Preferably, the actuating member has a radially outwardly projecting annular rib for engagement with a radially inwardly projecting tab portion of one of the contact plates.
An additional contact plate may be provided which has a portion engaged with another planar surface portion of the housing, disposed approximately in the same common plane as the first and second contact plates and in arcuately spaced relation to the other surface portions and in radially spaced relation to the axis. The additional contact plate and one of the first and second plates have interengagable contacts. By appropriate dimensions either a make-before-break or a break-before-make action may be obtained, as desired.
In accordance with further specific features, the actuating member has an integral piston portion projecting therefrom in one axial direction, preferably having a reduced diameter end portion receiving an O-ring seal member. The actuating member further has an integral portion projecting axially therefrom in the opposite direction and into the center of a coiled compression spring, serving to act as a spring guide.
An additional very important feature relates to the provision of terminal posts which extend in directions parallel to the central axis of the switch and which have base portions extending through arcuately spaced openings in an annular rim portion of one housing member, thence through openings in contact plates, and thence through openings in an annular rim portion of a second housing member, the terminal ends of such base portions being provided with rivet means to secure the rim portions together and to clamp the contact plates in position. This arrangement is highly advantageous, not only in simplifying assembly but also in insuring the proper assembly of the switch in a manner such as to obtain reliable switching action.
This invention contemplates other objects, features and advantages which will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings.